<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
<head>
<style>
.dropdown {
    position: relative;
    display: inline-block;
}

.dropdown-content {
    display: none;
    position: absolute;
    background-color: #f9f9f9;
    min-width: 160px;
    box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
    padding: 12px 16px;
    z-index: 1;
}

.dropdown:hover .dropdown-content {
    display: block;
}
</style>
</head>
<body>
<h1>可悬停的下拉菜单</h1>
<p>请把鼠标移到文本上，已查看下拉内容。</p>
<div class="dropdown">
    <span>把鼠标移到我上面</span>
    <div class="dropdown-content">
    <p>Hello World!</p>
    </div>
</div>
</body>
</html>